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Ok, so when I checked the sizes of the strings to mark the bridge for the approximate size of strings to replace, i noticed that the piano is very irregular in its stringing scale. I assumed it would start at a larger size in the low tenor, and then progress in steps to a smaller size in the high treble. For some reason It starts at a size (I think it may be 17) and then increases to a larger size (17 1/2), and then way down to a smaller size (14 1/2). This is a 1928 Hobart M. Cable grand. Should I be accurate in duplicating the sizes I'm finding, or should I restring with the suggested scale in "A guide to Restringing" by John W. Travis? Thanks. Oh, and by the way, Ari Isaac is duplicating my hammers and bass strings! I can't wait to install them!

For your purposes at this point, I recommend carefully measuring each speaking length of the plain wire unisons and use the Klepec chart in Mr. Travis's book to figure a smoother scale. Keeping the tension as smooth as possible will be the most important consideration. If you use the wire sizes you found on the piano to see what the tension and other values would be from the chart, you will find that the values will be very irregular as you suspected. I had very good results back in the late 1980's using that chart to refigure plain wire scales of lesser known grands and verticals. It's best to start on note 88 and work your way down. In a few cases, scales can drop back a half wire size or so for a couple of unisons as they cross a plate strut.

It is difficult to determine the gauge from micrometer readings. Wire might have some irregularities, and dirt, corrosion and bends in the wire throw the readings off.

I use a spreadsheet to determine a scale with an even tension. My goal is to avoid great leaps of tension, and try to keep the difference between adjacent notes to no more than about 5 pounds, although this is not always possible. Most old pianos were not designed with this in mind, and tensions can vary wildly. I find that gauges to change too much in the treble and too little as you go to the bass.

I measure speaking lengths from a paper pattern such as used for bass strings. You can only do it to so much accuracy. Be especially careful in the treble: small inaccuracies make the biggest difference there.

Just to make sure, when you refer to the speaking length, what two points am I measuring from? Do the strings have to be tightened, or even in place? How do you get an accurate measurement with the plate in the way?

Is the Klepac Chart the recommended scale for pianos? For instance, is it strange to have a size 14 for C-88, or does it simply depend on the piano? It would be great if my make of piano was included in the vast charts in the back of Mr. Travis' book so that I had an accurate guide to go by.

The speaking length is from the front bridge point to the agraffe or capo bar. The best way to make a pattern is to start with the strings in place. Place the paper over the bridge pins and sandpaper them, so that the paper will hold in place. Then rub a pencil over the strings, so you get the direction that they go from the bridge pin. You can mark the other end of the speaking length if there are agraffes or if it is an upright. You will probably want to remove the bass strings, though. After you remove the rest of the strings, you can put the pattern back on the bridge pins, and use a pencil to mark the capo bar.

The Travis book is good for its time, but we can do better now, thanks to the computer. Since computers give quick results, I figure it out by looking at the spreadsheet, starting with the gauge of C-88 and that of the lowest plain string, although those are just guidelines. I usually start by looking for 160 lb. across the scale. It can be less for shorter pianos, and more for longer pianos. If you start with that in mind, it usually works out.

What I really want to avoid is the huge dip in tension before the wound strings start. This is the problem of the hockey-stick bridge. If there is such a bend in the bridge, you may need to change gauges at every opportunity, even skipping a wire size. If you have some idea of what the wound strings are at the break, you can come close to matching the tension across the break. Plugging them into the formula will come close enough.

The results are a a scale that stays in tune better, and more even tone, so less voicing is required. I have posted this before and after graph before, but this is how it can work out:

Ryan, it's been many years since I used the Klepac chart, so I looked it up. I forgot that it does not give you any direct info on the variables that there will be: pounds tension, inharmonicity and percentage of breaking point but you can still use it just as effectively as if you did have all that information. You can still come up with the exact same determination as you would if you had a computer spread sheet or another book I have which does give all of that information.

First, to answer your question about how to measure, it is actually easiest to measure speaking length with all of the strings removed. Start on note 88 and for the first several notes, just use a pocket technicians ruler or other very small ruler and measure from the forward bridge pins to the termination point on the plate. The first measurement should be about 2". As the instructions say, if it is longer than that, you will use a larger size wire.

Some pianos do have size 14 wire at the very top. Older Kawais come to mind. But if your piano has size 14 up there and your measurements are closer to what that chart has, use what the chart says. Since you won't have all of the information, you'll have to make some careful decisions but in the end, even if you could see all of the variables, you'd end up making the same decision as you would with much more information with the limited information you do have using this chart.

Most scaling decisions will run with patterns of 2, 4 or 6 unisons of the same size wire before they change to the next. As you get down further, use a long but fine tape measure. You may have to have someone help you but I have measured the longer strings by myself simply by hooking the tape measure on the forward bridge pin and pulling it taut and then finding the length at the other end, trying to estimate just where that termination point would be with an agraffe involved, etc. Patterns of 8 or more strings in a row in the tenor are common and it is also common to sometimes skip a whole wire size once you get to size 18 and larger.

It's just as well that your piano's string sizes are not listed in the book because if they were, it would just be what was found there and you would be simply repeating a manufacturer's error. Some of these pianos were made very poorly, just using a few sizes of wire. It was faster and cheaper but certainly not better. So you can make a better, more evenly tensioned scale by using the Klepac chart.

Does the piano you are working with have wound strings in the low tenor? If so, that is good but I suspect it is one of those with the "hockey stick" type bridge with plain wire down to about B2. If this is so, the best improvement you could make is to convert those flabby low tenor strings to 2 string, wound string unisons. But because you do not have that capability at this point, there is a second alternative which will be far superior to simply putting on wire which is way too low in tension (size 18 wire all the way down to B2, for example).

Convert the lowest tenor string to two string unisons but use markedly heavier wire in that area. Depending on your measurements, all the way up to size 21 for the lowest note. Sometimes, this works out to something like size 21 for B2 only, then Size 20 for C3 and C#3, then size 19 for D3 and D#3. (Then have size 18, 171/2 and 17 regular 3 string unisons on up to about C4 and higher, depending upon your determinations). In such an example, you'd have 5, 2 string, plain wire unisons. You might skip a couple of hitch pins because of that. You would still put a tuning pin in the center hole but you just leave it blank with no string on it for appearance sake. If you can and have some 2 string agraffes to put there, go ahead but it is not entirely necessary. It might even work out better if you don't. Just put the 2 strings through the outside holes and leave the center blank.

The reason why it may work out better not to convert the agraffe to a 2 string type when doing this kind of change is that this larger sized wires will be very loud and brassy sounding. That's first of all why you would only want to have two, not three. If the hammer strikes at only the edges of this very powerful wire rather than more at the center, it won't be quite as strong of a sound. You'll still need to deeply needle these hammers to take down the power. But the benefit will be that this section of the piano will stay much better in tune than it would with smaller wire. The smaller sized wire also gives off a very "wolfish", "tubby" tone that is difficult to tune. It is extremely unstable when the relative humidity changes. The larger sized wire, while still a compromise, will be a better choice in the end with respect to both tone and stability.

Many small verticals are scaled this way. I rescaled many verticals and small grands this way back in the 1980's and still tune them today and I am still quite satisfied with the results, especially considering how simple and easy a choice it was to make back then with respect to any other far more complicated conversions that may have been possible.

Please tell us a little more about the characteristics of your piano's scale design, particularly the low tenor.

I see that BDB also answered while I was writing my message. Please read both carefully. You'll want to be able to do what he does at some time in the future. You might also be able to send him your measurements and he can send you back his suggestions for wire sizes when he runs them through his computer. Compare them to what you got by using the simple Klepac chart.

The first measurement should be about 2". As the instructions say, if it is longer than that, you will use a larger size wire.

This is an example of outmoded information. The longer the string, and/or the thicker the wire, the higher the tension you need to get the same pitch. So if the first measurement it more than 2", and you want to keep the tension reasonable, you need to lower the wire size.

Ok. I found a super-small measuring tape and was able to find that C-88 speaking length is 3 1/8" or 3.125". According to the Klepac Chart, that would be a size 14. That is what is installed. I checked the low tenor. I have plain wire strings starting at the 27th note (B3). So I have 26 unsions of copper-wound strings. The speaking length of the lowest tenor string is 37.1875" or 37 3/16". According to Klepac, a sz. 19 is suggested. That is what is installed.

The bridge curve is sort of like this:__ \ \ \ \____I know that's a really poor example, but that's a rough idea. Almost a backwards "S".

BDB, I'm not afraid to admit my ignorance. I don't understand how you came up with the spreadsheet. What formula is it that you refer to? Is it one of the many formulas explained in Travis' book? If I record the speaking lengths of the plain wire strings, would you be willing to enter them into your computer and figure out what wire sizes to use? I'd be intersted in comparing the outcome to what I get from the Klepac chart.

I just finished measuring the string sizes in the piano. Beginning with C-88 and going down:

What does that say to you experts? Seems to me that it's a poorly scaled piano. But if I knew what I was talking about, I wouldn't be on here asking for your help. ha-ha I appreciate your time and input. Thank you in advance to all.

3.125" is way too long for C-88. Any string that you put in there would probably break. #14 would be 428 pounds!

It is very unlikely that you measured those gauges correctly, and you seem to have trouble measuring the speaking length as well. I do not know what piano you are working on, but designers who did not do any calculations usually followed conventional practices. If they were using only full sizes, then there would be about 6-8 notes of #13, then a similar number of #14, with maybe more for #16 and 17, and a little less for larger sizes. Incidentally odd numbers of unisons means that some strings have to be individually tied, rather than looped around the hitchpins, so 5 #17 and 3 #19 would be unusual. Designers who used half-sizes changed more often in the treble, and usually abandoned half-sizes in the tenor, which is bad practice.

The formula I used was adapted from The Piano-Its Acoustics by McFerrin. For a given pitch p, length l and tension t, the gauge is:

((SQRT(t)/(0.04796*p*l))-0.025)*500+10

You can solve for the other variables if want to guess a gauge and find out what the tension is or do something like that.

Piano scaling is really advanced stuff. With respect, if your measurement of the speaking length of C-88 comes to 3 inches, you need to let someone else check the scale and tweak it for you. Practice stringing, tuning, voicing and work your way up to higher skills.

Well my bridge illustration didn't turn out like it was supposed to. ha-ha I rechecked the speaking lentgh of C-88. How does slightly over 2" sound? According to the Klepac that would be a sz. 13. So, according to BillBremmerRPT, the easiest way for me to restring this 1928 Hobart M. Cable grand is to just use the Klepac chart as a guide. Correct? Especially for someone as inexperienced as me. Thank you so much for your help.

Just as I said, Ryan but I do take BDB's comments seriously. When I read the note in Travis' book, there did seem to be something backwards about it but the hour being late, I let it go. To create wound strings is highly complex but the fact is, for the plain wire, the choices are very limited. Therefore, using that chart or this other book I have, a Handbook of Treble String Tensions, one can come up with the same results as any more advanced program. But you have to be sure about what you are doing. Measure the *speaking length* of the string only (not to the far side of the bridge). Also, the note that you identified as B3 is actually B2. The lowest B of the piano is B0.

To use #19 wire in the lowest part of the plain wire section will work, yes. But I still recommend doing what I suggested in a previous post: convert the lowest plain wire notes to 2-string unisons. Use size 21 wire for B2 only, then #20 for C3 and C#3 and then size 19 for whatever else would require size 19. That would mean just 3, 2-string unisons in this case. I think BDB might agree with me there. If you can accurately measure all of you plain wire unisons, send BDB the data. He can create a nice smooth scale for you easily and quckly.

I think BDB might agree with me there. If you can accurately measure all of you plain wire unisons, send BDB the data. He can create a nice smooth scale for you easily and quckly.

If you ask nicely, I might send a blank spreadsheet. Filling in 60-odd numbers is a lot of my valuable time. I think I can convert it to Excel.

Tolerances in measuring are very tight, particularly in the high treble. That glitch in the graph at B-87 is probably because I was off on the speaking length by 1/32" or so. "Slightly over 2 inches" does not cut it. You have to be within about 1/64" there.

Yes, Ryan, a very important distinction. The first 3 notes, A, A# and B are the "zero" (0) octave. I ran into this problem last Wednesday when tutoring an aural tuner about passing the exam. All ETD's identify the notes of the piano using the system devised by Hermann Helmholz, a 19th Century scientist who gave us knowledge about many aspects of tuning theory. Some people still identify the notes of the piano from 1-88 but the identification by octave number and note is a lot easier to learn. The PTG Tuning Exam uses this system because ETD's are used to measure and score the exam.

So, the lowest C is C1. Middle C is C4. The very highest C is C8. The C an octave below middle C is C3 and the C an octave above middle C is C5. This is a good thing to get used to knowing whether you ever use an ETD or not. Only the Bosendorfer Imperial Concert Grand has a full octave of notes all the way down to C0. Some very old pianos stop at A7 (an 85 note keyboard instead of 88).

The piano you are working on is a classic example or "poor" scale design. But there are many of them out there. A Yamaha GH1, for example has B2 as it's lowest note in the tenor. That note has a very bad sound and is difficult to tune. No ETD calculated program will get it right. I have consistently found that it must be tuned quite a bit sharper than the C3 next to it for it to sound in tune. At one time, Yamaha supplied conversion kits to change the lowest six unisons of the tenor section to wound strings. I have one piano teacher customer who has such a piano and did the conversion. It solved the tone and instability problems in that area of the piano. Yamaha also made (and possibly still makes, I don't know for sure) the very same model with the six lowest strings in the tenor being wound, 2 string unisons.

However, converting the low tenor to wound strings is quite a complex job. You need to add extra hitch pins because each wound string as a single loop at the end. You use a smaller core wire and a fine copper winding. Only someone with a scale design program could calculate the core diameter plus the winding thickness and winding length. So by comparison, the compromise made by simply putting heavier core wire but only two string unisons is by far, easier and simpler.

I noticed immediately the scale design of the new, smaller Walter grand when I first saw one. Del Fandrich created the design. It is similar to what the smaller Mason & Hamlin and A.B. Chase pianos have. It has a separate, small low tenor bridge with 4 wound strings on it. When I played across the transition (break) from the low tenor to the bass, I heard the most even tone I have ever heard from a small piano in this area. There was, to my ear, absolutely no distinction in tone from one note to the other across this span of the scale. This is the ultimate goal.

While putting wound strings in the low tenor improves most small pianos with a long tenor bridge, there always seems to be a difference in tone across the break. Take a Steinway model M for example. The Steinway Model A also has wound strings in the low tenor. One model of the new Estonia grands also replicates this design. It seems that a better compromise for many small pianos is to simply make the bass bridge longer. This is what Kawai has done with its new baby grands. The Steinway L and O still have a low tenor with plain wire. Any experienced piano tech will tell you that this area of the piano is the most unstable and difficult to tune and voice. I would be tempted to convert the 3 lowest unisons of a Steinway L if I were to rebuild one but somehow, Steinway's designs are considered "sacred". I've never seen one that was converted but I imagine that some people have done so.

Having said all of that, the simple change from three to two string unisons with heavier wire in the three lowest notes of the tenor of the piano you are working on would be just the thing for you to do at this stage of your career as a piano technician. You won't regret it.

This is the spreadsheet. This has numbers filled in it, from the piano in the chart, but you can overwrite them. Do not overwrite the pitch numbers, or the formulas. Work on a copy, not the original!

Enter the speaking lengths in the column "Length 1". Enter target tensions in "Tension 1". "Gauge 1" will give the approximate wire gauge to give that tension, although in finer degrees than wire comes in. As you can see, I was aiming for about 150 lb. across this scale. In general, longer pianos will give you higher tensions. It is not necessary for the tension to be a constant. Particularly in very long pianos, you might want to have it gradually increase as the strings get longer. Even this one decreases tension somewhat, since it is a short piano.

Then you can enter the gauges you choose into "Gauge 2" and see what the resulting tension is in "Tension 2". "Length 2" is just copied from "Length 1". This helps refine the numbers.

If you are designing a new bridge, you could use the "Gauge 3" and "Tension 3" to refine the speaking lengths.

Use this at your own risk. I make no guarantees for accuracy or suitability of the results.

(I am not an Excel expert, so I cannot give instructions on how to use it, like how to fill columns. I actually use another spreadsheet application, and this is just a translation into a more common application. So do not ask me for help with that.)

Just curious BDB - how do the string length measurements come out to the ten-thousandth of an inch (e.g. 24.063")? It seems to me that it would be nearly impossible to meaure even to the 1/100 of an inch. Are you converting from a metric measurement?

Also, do I understand it correctly that inharmonicity and the loudness factor are not taken into account when coming up with a scale using this procedure?

Ryan, if BDB's offering seems a bit too overwhelming, just list your measurements, the best you can and I will calculate the pattern for you using my Treble Strings Tension Handbook as I did with so many pianos in years past. Start with C8 and list like this:

88 (C8):287 (B7): 2 1/3286 (A#7): 2 1/885 (A7): 2 1/4

etc. down to 27 (B2) (where your plain wire ends).

From notes 88-63, to the nearest 1/32" is sufficient. From notes 62-47, to the nearest 1/16" is sufficient. From notes 48-27 (27 is B2, the lowest plain wire on your piano), to the nearest 1/8" inch is sufficient.

If there are any unisons where one string is tied off, be sure to indicate this on your chart. Example:

65 (C#6) 6 1/32 Tied Off

******************************************************************

While I can see that if using a spreadsheet, you may want to have finer measurements and when converting to metric or English decimal, you would want to have 3 decimal places, as I've said from the beginning, the end result is always going to be a decision of one wire size to the other. The final result will look like just about any other piano, merely a difference sometimes of 2 or 4 more unisons of a particular wire size and conversely, less of another. If the piano you are working on really had size 14 all the way to C8, you can certainly expect that I or anyone else would come up with something like 4 unisons of 13 and 6 of 13 1/2 for the top 10 unisons.

In a few instances, you may see a particular wire size cross over the break from the treble to the tenor and in some rare cases, you may actually see the wire size decrease slightly across that break. It all depends upon the curvature of the bridge. Look at some small recent vintage Baldwin grands and you will see that.

To answer Jurgen's question about volume and inharmonicity: I agree with BDB that maintaining the smoothest possible curve of tension is the primary goal. When this is done, the inharmonicity curve inevitably follows suit. The volume factor does as well. Volume and inharmonicity go hand in hand with tension. If you have dips and peaks in tension, you will also have dips and peaks in inharmonicity and volume. Therefore, if you build the smoothest possible tension curve, you will have the best tuning stability, ease of predictable tuning, either aural or electronic and the least amount of voicing problems.

The volume issue does however start to be a problem in the low tenor when you get to the larger sizes of wire and are trying to maintain your tension curve. That is why I am suggesting and will most likely end up suggesting a few two string unisons in the very low tenor if Ryan posts his data.

I ran the inharmonicity numbers on one scale, and there was a slight increase near the break, but it was less than 0.02%. I may be interpreting the numbers wrong, but the important thing was that it was negligible.

Remember, none of these things were calculated when the pianos were designed.

Indeed. Many manufacturers just made some kind of curved bridge, others a kind of straight one and just laid on some wire with little more thought to it than that. When they ran out of room in short pianos, they just made the bridge take a left turn at the end and when they found that any wire heavier than size 19 sounded too loud, they just used lighter wire to the end of it. I've seen all too many pianos with size 18 wire all the way down to B2 on a 5'2" grand. Absolutely horrible sound and even worse tuning stability.

Fewer spools of wire meant a less costly inventory and less confusion for the stringer. Heavier wire sizes are harder to handle and were perhaps more expensive. Any rebuilder today can make a substantial improvement with no other alterations than carefully selected wire sizes.

As you can see from the spreadsheet, although the lowest strings of the sample piano are thick, most of the strings are thinner than usual. (There are 22 #13 notes!) This would have been much cheaper, because there is more length to the pound using thinner wire.

Any way you feel comfortable, Ryan. If you post on the Forum, I will return my caluculations here and they will be open to scrutiny which I am not afraid of but others may have slightly different opinions, so it's up to you.

If you send them by private e-mail, you may use an attached file. Put the words "piano scale data" in the header. If you respond privately, I can still post an abbreviated summary such as "6 unisons of 13, 4 of 13 1/12, etc. My e-mail address is Billbrpt@aol.com.

Oh, and be sure to let us know which notes do not share a string with an adjacent note. Otherwise I will assume that they all do, in which case there needs to be an even number of notes with each wire gauge.

I am playing around wih a scaling spreadsheet these days. Unless it is some kind of a secret, I would be interested in seeing the raw data (speaking lengths and, if available, original wire gauges) and run the numbers through the sheet I have, in order to compare with other programs.